This invention relates to electrical power machinery and, more particularly, to electrical motors or generators having a reduced axial length such as those used as driving components in centrifugal pumps.
Most electrical motors of the prior art include yoke and soft magnetic stators sections that penetrate the windings. These sections are magnetically inactive and contribute to power losses, and excessive size and weight.
The instant invention results from an attempt to provide efficient electrical motor elements, such as those used in centrifugal pumps, that require short axial lengths.
The principal and secondary objects of this invention are to provide efficient and compact electrical power machines having no magnetically inactive winding portions and a relatively short axial length. Electrical motors of this type can be effectively used as the driving components of centrifugal pumps.
These and other valuable objects are achieved by using a magnetized rotor preferably having a spherical shape.
The matching bowl-shaped stator comprises a circular yoke concentrically surrounding the rotor and a winding consisting of a plurality of segments mounted against the inner wall of the yoke in alternating sequences and obliquely oriented segments in relation to the motor axis of rotation. The yoke is preferably made of a composite of particles of ferro-magnetic material each coated with an electrically non-conductive layer.
In the preferred embodiment of the invention, a waterproof septum is installed in the air gap between the rotor and the soft magnetic yoke so that the rotor can be integrally formed with the impeller and immersed in the pump fluid.
While the spherical configuration of the motor yield the most efficient short axis machine, a frusto-conical or even cylindrical configuration may be chosen for ease of fabrication while retaining the principal advantages of the invention.
The inner surface of the yoke against which the winding is mounted is concentric with the motor axis of rotation but not necessarily parallel to it as it is in a cylindrical version. That inner surface may be axially linear as in a cylindrical or frusto-conical design or non-linear, that is, arcuate or in a complex broken line configuration.
The same efficient configurations can be advantageously applied to the design and construction of other electrical machines such as generators as well as electro-magnetic instruments such as compasses, galvanometers and any other devices that include electro-magnets.